Customer:       I bought two expensive dictionaries here half an hour ago, but I forgot to take them with me.

Manager:   Who served you, sir?

Customer:   The lady who is standing behind the counter.

Manager:   Which books did you buy?

Customer:   The books which are on the counter.

Manager:   Did you serve this gentleman half an hour ago, Miss Roberts?

                     He says he’s the man who bought these books.

Miss Roberts:  I can’t remember, sir. The man whom I served was wearing a hat.

Manager:   Have you got a hat, sir?

Customer:   Yes, I have.

Manager:   Would you put it on, please?

Customer:   All right.

Manager:        Is this the man that you served, Miss Roberts?

Miss Roberts:   Yes, sir. I recognize him now.